audio: Implementation of audio I/O, part II

This patch implements audio I/O for the synchronous, non-MMAP
case.

Updated the StreamDescriptor structure to make it usable.
Clarified comments on the expectations for the client and
the HAL module.

Bug: 205884982
Test: atest VtsHalAudioCoreTargetTest
Merged-In: I09651c6e80a397c80870622ac19234b4d4a38cbb
Change-Id: I09651c6e80a397c80870622ac19234b4d4a38cbb
(cherry picked from commit 01803d454ac192f4b6b732944f0be324b1b03a7f)
diff --git a/audio/aidl/default/main.cpp b/audio/aidl/default/main.cpp
index aeb9983..15874a0 100644
--- a/audio/aidl/default/main.cpp
+++ b/audio/aidl/default/main.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#include <cstdlib>
+#include <ctime>
+
 #include "core-impl/Config.h"
 #include "core-impl/Module.h"
 
@@ -25,6 +28,9 @@
 using aidl::android::hardware::audio::core::Module;
 
 int main() {
+    // Random values are used in the implementation.
+    std::srand(std::time(nullptr));
+
     // This is a debug implementation, always enable debug logging.
     android::base::SetMinimumLogSeverity(::android::base::DEBUG);
     ABinderProcess_setThreadPoolMaxThreadCount(16);